A new report finds that California could lose most of its beaches by the year 2100, due to rising sea levels. NPR's A Martinez goes to the beach to find out what can be done.

Transcript

A MARTÍNEZ, HOST:

Imagine California without beaches.

SEAN VITOUSEK: We looked at future erosion potential going into about the year 2100, you know, and we found that depending on the sea level rise scenario, California might lose about a quarter to three-quarters of its beaches.

MARTÍNEZ: That is Sean Vitousek, a researcher for the U.S. Geological Survey based in Santa Cruz, Calif. He authored a study using satellite images going back decades, then combined those images with models of climate-crisis-driven sea level rise. Vitousek says it wouldn't take much rise to lose a lot of coastline.

VITOUSEK: The rule of thumb is basically for about every meter of sea level rise, you're probably going to get about 30 meters of coastal erosion happening. So when you get into three meters of sea level rise, you're talking almost 100 meters - you know, 300-plus feet of erosion under those large scenarios. Not to mention the flooding challenges that are also associated with sea level rise - you just have more severe and more frequent floods associated with waves.

MARTÍNEZ: Vitousek's study is a prediction of what may happen. And while he's confident in it, he admits having healthy skepticism is always important. So I got a second opinion. Because California losing 75% of its beaches - I mean, those numbers just can't be right.

KATHLEEN TRESEDER: Yeah, they look right. They're consistent with his previous study. He used a different approach. And so whenever we have two approaches like that that arrive at a similar conclusion, that makes me feel like the results are relatively robust. So I do believe it.

MARTÍNEZ: Kathleen Treseder studies and teaches climate change at the University of California, Irvine. I met her at Sunset Beach in Orange County. It's one of the places in Southern California that Vitousek says is most feeling the effects of coastal erosion. As we were standing on the sand on the edge of the Pacific Ocean, things kind of looked all right to me. There's a long row of what probably are very expensive places to live on either side of us. And people were hanging out, having fun in the sun. So I asked Treseder, why should they be worried?

TRESEDER: Well, because as we have the sea level rise - as you can see, this is a very shallow area. The sand doesn't go up uphill to the houses very steeply, right? So these houses are actually - it looks like within about 10 feet of the ocean right now. And so just from normal sea level rise, just without even any waves, you know, the waves should be lapping at their porches by the end of the century. But then when you add these big storm surges, that's just going to take out these homes. I mean, these homes were not designed to be battered by really severe waves.

MARTÍNEZ: Do you think that people who live here right now kind of realize that, or are they maybe putting it behind them or at the back of their minds as much as possible?

TRESEDER: I - well, looking here, there are a number of homes that are being renovated. There are some that clearly were renovated lately. I mean, if I were a homeowner, I wouldn't be doing that if I were worried about it. My guess is they probably don't realize.

MARTÍNEZ: So a place like Sunset Beach here, what kind of things could they do, if at all, to try and survive it or at least try and not let this happen?

TRESEDER: Well, there are a few different things they can do. Some are short-term. Some are long-term. Like, some are like the Band-Aid, and others are like the cure. So the short term is that as the sand washes away, they can just truck in more sand and just keep adding more sand as the sand washes away. You can imagine that that is not sustainable.

The next thing that they could do is potentially put in infrastructure. So some cities have put in - where there's cliffs that are in danger, they'll harden the cliffs. So they'll put, like, concrete on the base of the cliffs or big boulders. That's an option. Here where there's no cliffs like that, you could potentially put - use some green infrastructure out - just out into the ocean where you can make, like, a barrier island that would break those waves. So if the waves hit a barrier island, then they lose their energy. It won't hit the beach so hard. That's, like, medium.

The long-term solution is just we have to reverse climate change. You know, the ocean is going to do what the ocean is going to do. And we can, you know, stop it to a certain extent. But we're nowhere near as powerful as the ocean. So we're kind of at its mercy.

MARTÍNEZ: In addition to teaching at UC Irvine, Treseder is on the Irvine City Council. Now, Irvine is not a city on California's coast. It's around six miles inland from where we were standing. So how does coastal erosion and sea level rise affect what Treseder does in Irvine?

TRESEDER: You'd be surprised. So the deal is that we are landlocked, but we are intricately connected with the Newport Bay and the ocean because we have a creek, the San Diego Creek, that drains all the water off the city, down into the bay and into the ocean. So it's our job as a city to be good neighbors and to make sure that we, for instance, remove all the pollutants that are coming off the city into the water.

So we actually have built a natural water purification ecosystem. And as it goes through the marshland, it cleans it almost entirely - removes pollutants. Then when that goes into the bay, we're not causing any problems in the bay. Now, as sea levels rise, it's actually going to inundate that marsh community. And so it won't be able to work the way it's supposed to. So that means that these pollutants would be going right into the ocean.

MARTÍNEZ: And are there other cities that are in the same situation as Irvine where if sea level rise occurs, it could actually affect some of the things that you're talking about in Irvine?

TRESEDER: Yeah, there are creeks and rivers that drain offshore into the ocean all up and down the coast. We are connected. Just because we're a bit inland doesn't mean that we don't affect the ocean. And so that's true for really any city along the coast that has that sort of connection with the rivers or the creeks.

MARTÍNEZ: Do you see any hope?

TRESEDER: Well, no, I do have hope. I have to. I'm doing all this work to try to combat climate change. You know, humans change the atmosphere one way - we can change it back, for sure. It's just the question of the will of the people. So, you know, we're up for it. And I imagine that we're not all that different from many places around the world.

MARTÍNEZ: That's Kathleen Treseder, professor of climate change at UC Irvine and a member of the Irvine City Council. Transcript provided by NPR, Copyright NPR.